Method of malleableizing cast metal.



WIG. WEBSTER. METHOD OF MALLEABLEIZING CAST METAL.

APPLICATION HLED JAN. 9, IHB.

Patented M211. 25, 1919.

lV/7l VESSES s PATENT OFFICE.

WALTER G. WEBSTER, OF HIGHLAND PARK, MICHIGAN, ASSIGNOR 0F ONE-THIRD TO HUGH IRELAND, OF DETROIT, MICHIGAN.

METHOD OF MALLEABLEIZING CAST METAL.

Specification of Letters Patent.

Application filed January 9, 1918. Serial No. 211,058.

lowing to be a full, clear, and exact descrip- 1 tion of the same, such as will enable others skilled in the art to which it pertains to make and use the same, reference being had to the accompanying drawings, which form a part of this-specification.

, The principal ob'ect of this invention is a method of malleableizing cast metal ina materially less period 'of time than is possible by present known processes whereby a greatly increased output may, result, and the cost of malleableizing metal reduced to a minimum. In the method of malleableizing cast iron articles at present in general use, the articles are placed in a box and packed with substances containing oxygen as iron filings, with charcoal, etc., and a number of packed boxes are placed in an annealing furnace and the articles therein brought up to the necessary temperature-namely, about 1650 degrees F., and thereupon the furnace is allowed to gradually cool. The period of time consumed in producing malleableized castings'under such well known system is from about seven to twelve days. I have found by experiment that a considerable period of time is required to heat the packed articles'to the required degree due to the fact of their being insulated by the packing, and

that the time required to cool the'articles to the necessary degree before removal from the furnace is likewise increased by reason of the insulation of the castings by the packing. It is further known that a packing is often utilized that does not contain an appreciable quantity of oxygen, in which case the principal purpose of the packing appears to be the exclusion of air and thus preventing formation of a scale or skin-harden ing of the castings.

With the method which is the subject matter of this application, the castings are gas packed, excluding oxygen, but not to any great extent insulating the articles from the heat of the furnace whereby the articles may or rods.

be brought to the desired temperature within a short period of time and may be-cooled more rapidly than with the older method of packing mentioned and, by reason of the fact that the oxygen is practically wholly excluded from the articles being treated, the product is to some extent superior to the product of the older known processes in which oxygen may attack the iron.

It is further an object of the invention to provide a process that not only is a great saving in the time required to malleableize the metal but in which the labor cost is re-' duced to a minimum in that the method of excluding oxygen is automatic in its operation, and that castings do not require to bepacked manually as in the older processes above mentioned. These and the several other objects and novel features of the process are hereinafter more fully described and claimed.

The drawing is a vertical section illustrative of a type of box or case in which the Patented Mar. 25, 1919.

cast iron articles are placed for treatment, a showing one manner of supporting the articles in the case, but it is to be understood that cases or pots of various shapes and sizes may be' utilized. An essential characteristic, however, in any type of case or box used is that it be possible to seal the same in a manner to prevent an inflow of air containing oxygen. The box shown in the drawing is in the form of a tube open at both ends.

The upper end is provided with a cap plate 2 which seats against a shoulder 3 of the case. The articles may be strung on a rod as indicated at 4, or small articles may be carried inbaskets on such rod as indicated,

at 5. The baskets are to be understood as being open in the top and bottom faces thereof to an extent to allow the gases within the case to circulate through the boxes. Several rods or bars may be used or a single 'rod carrying a large open basket for the articles depending onthe size and character of the articles to be treated. The plate 2- is apertured to allow the rods to extend therethrough as shown in the drawing, and the articles may be removed by pulling the rod The case (after being sealed at the bottom filled with the articles or with basketscontaining the articles as may be necessary and a small quantity of sawdust or Wood scrap, coal tar, or 011, or most anything'volatlle in character or adapted to give off a gas when heated to the proper degree is placed in the casing with thearticles. The case may be formed with a bottom integral with the side walls if desired, in which event the clay and sand for sealing may be dispensed with'at the bottom. In the event that the case is sealed at the bottom'with clay and sand as mentioned, the volatile material as sawdust or the like, is thrown into a case, there being 7 some placed 1n each of the baskets (if baskets be used), or if oil or tar be used, the articles may be each covered with some of the material and sufiicient volatile material- .At this temperature the castings have not become heated to such degree that the oxygen may attack or combine therewith and,

by reason of the combustion of the volatile material, the oxygen is entirely used up previous to the metalbecoming heated to such degree that the oxygen may combine therewith, and during the subsequent continued heating up to the desired temperature, the metals are really gas-packed to the exclusion of oxygen. In the older method in which a packing as iron filings was used,

a considerable period of time elapsed before the articles acquired the desired temperature. With the method of heating herein described, oxygen being excluded, the articles are not insulated as'in the old method and thus more quickly attain the; desired temperatnre and are more rapidly cooled resulting in a considerable saving in time.

With the older method of packing the castings the time required to anneal articles was from about seven to twelve days and with my improved method I have malleableized small cast articles in aperiod' of fifty-two hours, the metal being fully equal if not superior in malleability to the articles treated:

for seven days period with the older method .and being without the scale or skin-hardening as is desirable with a malleable casting. I des1re it to be understood that allarticles may, not be properly annealed in fifty-two.

hours by my method as thetime required to properly malleableize a casting depends largely upon its bulk. Articles having a these coagulations. v the metal is thus apparently produced by 130 comparatively small cross section of metal may be mallcableized in a-shorter period of time than articles materially greater in cross section as is well understood by thoseskilled in the art.

As heretofore stated, the pots or cases in which the articles are inclosed may be of various sizes or shapes depending upon the character of the articles to be treated, and the character or form of the case or pot forms no part of this invention, the illustration being only of a form of pot adaptable for the performance of the process. The essential characteristic of this process resides in heating the metal parts to the necessary degree of temperaturewhile non-insulated from heat except by the case and in the absence of oxygen during that period in which oxygen would attack or combine 'with' the carbon of the heated metal.

f I have malleableized castings by the described process'.,usi1 1g all of the various sub stances mentioned containing volatile matter with equally beneficial results, and I am therefore led to believe that the character of the gas given off by the volatile matter is of little importance, the principal value of the combustible material being that in the combustion thereof the oxygen within the case is consumed. It is further evident that the oxygen, in a form in which it may combine with the heated metal may be removed in various ways and secure anequally beneficial result. It is therefore tobe under-- stood that a particular feature of the invention is involvedin heating the cast iron articles to the necessary temperature practically in the absence of oxygen and the preferred method of exhausting the oxygen is by' the use of acombustible material although this may be accomplished by other equally efiicient methods.

It is evident that, in the use of a combustible material of the character stated to exhaust the oxygen, gas is produced containing' carbon dioxid and carbon monoxid and the metal attains the desired temperature in I the presence of a gas containing carbon. In

this method the metal is not decarbonized as with the methods at present in use, but

-micro photographs indicate that the following result is attained: In f the original castings the carbon is so thoroughly mixed withthe metal that apparently each molecule of metal carries with it substantially the same proportion-of carbon; After treatment by the method herein disclosed the" carbon appears to have separated from the molecules Of'il'On and gathered in small quantities comparatively uniformly distributed through the mass metal and being in v the nature of flakes of carbonwith comparai tively pure metal surrounding and inclosing The malleable-ness of separation of the carbon from the molecules and the segregation thereof within the mass of metal. v Having thus described my invention, what I claim and desire to' secure by Letters "Patent of the United States is- 1. The method of malleableizing metal consisting in placing the same in a hermetically sealed receptacle together with a quantity of material suflicient upon ,burning to exhaust the oxygen contained inthe receptacle and form gas in a sufficient quantity to produce pressure preventing an inflow of gas containing oxygen, subjecting the receptacle to heat for a sufficient period prior to mal leableizing metal and then allowing the same to cool while in the sealed receptacle:

2. The method of malleableizing metal consisting in placing the same in apractically hermetically sealed receptacle together. with a quantity of material adapted'to burn a at comparatively low temperature and in quantity suflicient upon ignition to exhaust the oxygen contained in the receptacle and form a gas of suflicient volume at the presquantity to fication.

sure developed preventing an ingressof gas containing oxygen, heating the receptacle till the metal therem has attained a temperature of practically 1650 degrees F., then al-' lowing the same to cool while in the sealed receptacle to a temperature not greater than 1000 degrees F.

3. In a method of malleableizing metal,

the .step consisting in heating the metal to the required temperature in a sealed recepbnrn at low temperature and in suflicient exhaust the oxygen within the receptacle.

4. In a method of malleableizing metal the step consisting in heating the metal to WALTER G. WEBSTER;

.tacle in the presence of matter adapted to 

